Here are two *very* good update-to-date sources of Rspec howtos and best practices:

The first on by Andrea Reginato(@lelylan) gives a very good overview. Start here:
https://docs.google.com/a/soundcloud.com/document/d/1gi00-wwPaLk5VvoAJhBVNh9Htw4Rwmj-Ut88T4M2MwI/mobilebasic?pli=1&hl=en

The second one by Jeff Pollard features ninja-kick-ass shared spec examples:
http://bitfluxx.com/2011/05/23/some-rspec-tips-and-best-practices.html

Andrea did already a good job with the Google Doc, but what about collection all tipps into git repo so everyone can easily collaborate - let’s fork, PR and drive it forward!

More sources to follow - spec it, run it, kick it!

[kind of unrelated but nice picture ‘borrowed’ from global nerdy]